The present disclosure relates to fuel tank valve apparatus, and particularly to a liquid fuel filter for use with a fuel vapor vent system in a fuel tank. More particularly, the present disclosure relates to a system for venting fuel vapor from a tank to a vapor recovery canister without excessive carryover of liquid fuel from the tank to the canister.
Vehicle fuel systems include tank-mounted valves for venting pressurized or displaced fuel vapor from the vapor space in a fuel tank to a vapor recovery canister located outside of the fuel tank. The canister is designed to capture and store fuel entrained in fuel vapors that are displaced and generated in the fuel tank during a typical vehicle refueling operation or that are otherwise vented from the fuel tank.
However, it is not desirable to discharge excessive amounts of liquid fuel into the vapor recovery canister. This is especially true during xe2x80x9cmaneuveringxe2x80x9d of fuel tank vapor control apparatus mounted on a moving fuel tank of the type that occurs during xe2x80x9cdynamicxe2x80x9d testing of such vapor control apparatus. It is therefore desirable to minimize the amount of liquid fuel carryover from the fuel tank to the vapor recovery canister of the type that might occur during dynamic testing or other vehicle operation.
According to the present disclosure, a vent module is adapted to be mounted in a top wall of a fuel tank to vent fuel vapor from the tank to a vapor recovery canister located outside of the tank. An outer shell is positioned around the vent module to define a fuel vapor transfer passageway and a liquid fuel accumulation chamber.
Fuel vapor inlet and outlet ports are formed in the vent module to allow flow of fuel tank vapor through a valve chamber provided in the vent module to the canister. The fuel vapor inlet port receives fuel vapor exiting the fuel vapor transfer passageway. The vent module includes a valve movable in the valve chamber to block flow of fuel vapor from the tank to the canister through the fuel vapor outlet port.
The outer shell includes a fuel vapor transfer port arranged to xe2x80x9cabovexe2x80x9d the fuel vapor inlet port formed in the vent module and to admit fuel vapor from the tank into the fuel vapor transfer passageway provided between the vent module and the outer shell. The liquid fuel accumulation chamber is located below and in fluid communication with the fuel vapor transfer passageway to receive liquid fuel shed from fuel vapor flowing in one direction through the fuel vapor transfer passageway as that fuel vapor is forced to flow in another direction from the fuel vapor transfer passageway through the fuel vapor inlet port into the chamber provided in the vent module.
In preferred embodiments, the outer shell is retained in a fixed position relative to the top wall of the fuel tank to position the fuel vapor transfer port at a somewhat high elevation near a ceiling established inside the fuel tank by the top wall. The outer shell is formed to include a drain port so that liquid fuel accumulated in the accumulation chamber will drain back into the liquid fuel reservoir in the tank once the fuel level recedes to a height in the fuel tank below the drain port.
During tank venting conditions, displaced or pressurized fuel vapor passes from the tank through the fuel vapor transfer port from the tank into the fuel vapor transfer passageway provided between the vent module and the outer shell. The fuel vapor flows in a downward direction in the fuel vapor transfer passageway from the higher elevation fuel vapor transfer port formed in the outer shell to the lower elevation fuel vapor inlet port formed in the vent module.
To enter the vent module through the laterally extending fuel vapor inlet port, the stream of fuel vapor that is flowing downwardly through the fuel vapor transfer passageway must change its flow direction. This xe2x80x9cchange of directionxe2x80x9d causes the fuel vapor to shed droplets of liquid fuel entrained in the fuel vapor. Those droplets fall downwardly through a lower portion of the fuel vapor transfer passageway into the liquid fuel accumulation chamber while demoisturized, relatively dry fuel vapor flows into and through the vent module to reach the vapor recovery canister without xe2x80x9ccarryoverxe2x80x9d of any significant amount of liquid fuel from the tank to the canister. Any fuel entrained in this demoisturized, relatively dry fuel vapor will be captured and stored in the vapor recovery canister and later reused and burned in the vehicle engine in a well-known manner so as to minimize unwanted discharge of fuel vapor into the atmosphere.
Additional features of the disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the disclosure as presently perceived.